1. Field of the Invention
The present invention relates to a rotary spinning ring structure provided with a rotating ring, to be used on a textile machine, particularly, a spinning machine which uses a traveler for winding a yarn on a bobbin, such as a ring spinning frame or a ring twisting frame.
2. Description of the Related Art
Various rotary spinning ring structures of the kind have been proposed to solve problems in fixed spinning rings. However, those previously proposed rotary spinning ring structures have not yet been put to practical use because of their complicated construction, high cost and possibility of deteriorating yarn quality due to unstable rotation of the ring. Recently, rotary spinning ring structures of simple construction that makes the practical use of the rotary spinning ring structures possible were proposed in, for example, JP-A Nos. 2-26927 (reference 1), 3-51329 (reference 2) and 8-209470 (reference 3). Each of a the rotary spinning frame structures proposed in the references 1 and 2 comprises, as principal components, a ring support member of a synthetic resin, and a rotating ring of a carbon steel or an alloy steel rotatably supported on the ring support member.
The rotary spinning ring structure proposed in the reference 3 is a negative rotary spinning ring structure comprising, as principal components, a stationary tube mounted on a ring rail coaxially with a spindle, a sliding ring fitted in the stationary tube, a steel rotating tube supported coaxially with the spindle on the sliding ring in the stationary tube, a traveler put on an upper portion of the rotating tube to guide a yarn so as to be able to revolve on the rotating tube, and a braking means including a braking ring and associated with a lower portion of the rotating tube. In this prior art negative rotary ring structure, the traveler is caused to slide for revolution along a flange formed on the rotating tube by a yarn being wound on a bobbin when the bobbin rotates together with the spindle. Consequently, the rotating tube is dragged frictionally for rotation by the traveler. The revolving speed of the traveler is always lower than the rotating speed of the bobbin, so that the yarn is wound on the bobbin at a rate corresponding to the difference between the rotating speed of the bobbin and the revolving speed of the traveler. The rotating tube rotates at a rotational speed lower than the revolving speed of the traveler due to its inertia in an initial stage of a spinning operation in which the bobbin is accelerated and the rotational speed of the bobbin increases continuously, and hence the traveler slides along the flange of the rotating tube for revolution in a mode in which a traveler slides along the flange of a fixed spinning ring. After the rotational speed of the bobbin has reached a predetermined operating rotational speed, the rotary tube rotates at a rotational speed substantially equal to the revolving speed of the traveler and hence the traveler does not move relative to the rotary tube. During the deceleration of the bobbin to stop the spinning operation, it is possible that the rotating tube and the traveler decelerate more slowly than the bobbin due to the inertia of the rotating tube. Therefore, the rotating tube is braked by the braking means so that the rotating tube and the traveler may decelerate according to the deceleration of the bobbin.
The inventors studied the prior art rotary spinning ring structure proposed in the reference 3 and conducted spinning experiments using the same rotary spinning ring structure to put the rotary spinning ring structure to practical use. It was found through the spinning experiments that, although the rotating tube rotates smoothly with the revolution of the traveler and the yarn can be wound on the bobbin, a yarn of some type is liable to be broken when the spindle starts rotating after the broken yarn has been pieced and such a yarn requires skilled yarn piecing technique, that a balloon produced by the yarn is liable to collapse when the traveler and the rotating tube start deceleration while the traveler and the rotating tube repeat acceleration and deceleration alternately according to the vertical movement of the ring rail for a cop building operation, and that the yarn stiffens and the elongation of the yarn reduces to deteriorate the quality of the yarn when the yarn is wound on the bobbin by using the rotary spinning ring structure. Such a tendency is particularly conspicuous when the spindle is rotated at a high rotational speed not lower than 15,000 rpm, such as 20,000 rpm.
It was found through the examination of those problems found through the spinning experiments that the principal cause of those problems is the excessively large weight of the rotating tube and the resultant incapability of the rotating tube to rotate properly according to the revolution of the traveler. Steel rotating tubes (rotating rings) of 45 to 70 mm in inside diameter of the rotary spinning ring structure disclosed in the references 1 and 2 have a considerably large weight in the range of 43 to 200 g. The reduction of the weight of the rotating tube is one of measures to improve the capability of the rotating tube to rotate according to the revolution of the traveler. A lightweight rotating tube may be formed by molding a synthetic resin. The same idea as that is found in JP-U No. 52-51422. This idea proposes a combination of a relatively large traveler and a carbon-fiber-reinforced plastic conical ring.
The inventors found through spinning experiments using a rotary spinning ring structure provided with a synthetic resin rotating tube that the reduction in weight of the rotating tube is effective in improving the rotation of the rotating tube according to the revolution of the traveler, and that the deterioration of the yarn quality can be avoided when the weight of the rotating tube is less than a certain weight. Thus, no practical problem occurred if the rotating speed of the spindle was below 15,000 rpm. However, when the rotary spinning ring structure is used on an advanced spinning frame which operates at a high spindle speed not lower than 15,000 rpm, the rotating tube may possibly be melted by heat generated in the traveler or a bearing member if the rotation of the rotating tube is obstructed by some cause or if something is wrong with the bearing member. If heated excessively, the rotating tube gives out smoke or emits an evil smell and, if things come to the worst, the rotating tube burns, which is a problem in safety. The cost reduction of the rotary spinning ring structure also is a very important problem in view of realizing the practical use of the same.
Generally, synthetic resins are electrical insulators and are easy to be charged with static electricity. Static electricity accumulated on a portion of the rotating tube along which the traveler slides exerts particularly harmful influence. It was found that static electricity accumulated on the rotating tube attracts flies and dust to the rotating tube, flies and such fall off the rotating tube and are twisted into the yarn, the discharges of static electricity accumulated on the rotating tube at a high voltage give the operator an electric shock, and sparks and arcs generated by the discharges of static electricity cause waste fibers to burn, which may possibly cause fire.
If the weight of the rotating tube is not distributed uniformly and the rotating tube has a mass eccentricity with respect to its geometrical center axis, the rotating tube whirls and generates vibrations even if the mass of the rotating tube is small. Consequently, the resistance exerted by the bearing on the rotating tube assembly varies in a wide range, the magnitude of the resistance increases to deteriorate the rotating performance of the rotating tube and the revolving performance of the traveler, so that the tension of the yarn varies to deteriorate yarn quality or to cause yarn breakage. Vibrations generated by the rotating tube and the high frictional resistance exerted by the bearing to the rotating tube damages the bearing and shortens the life of the rotating tube.